Abstract
Cellulase and swelling agents are known to be effective in improving the colour strength of cotton. Nowadays, the handloom fabrics are much preferred due to development of innovative designs and their comfort in wearing Due to increased environmental awareness the use of natural dyes are much preferred in dyeing of handloom fabrics. But, khadi cotton has some major shortcomings like less dyeability. Keeping in view that the pretreatment of khadi cotton with cellulases, swelling agents and combination of cellulases and swelling agents before dyeing improves the colour strength properties, the present study was planned. The khadi cotton samples were treated with optimized conditions of enzymes and swelling agents. The optimum pH, concentration, treatment time and temperature selected for the acid cellulase enzyme treatment were 5.5, 1.5% (owf), 45 minutes and 50°C, respectively whereas in case of neutral cellulase enzyme, it was 7.5, 2.0% (owf), 70 minutes and 70°C respectively. The optimum concentration, treatment time and temperature selected for sodium hydroxide treatment were 20% w/v, 60 minutes and 60°C, respectively. In case of ethylenediamine, 80% w/v, 60 minutes and 70°C were selected as optimum concentration, treatment time and temperature, respectively. In case of zinc chloride treatment, the optimum concentration, treatment time and temperature were selected as 80% w/v, 60 minutes and 70°C. 5 g Butea frondosa dye extracted for 75 minutes gave best results on khadi cotton when dyeing was carried out for 90 minutes It was observed that out of various concentrations of mordants used with Butea frondosa dye, best shades of colour were obtained by using 0.04 g of Alum, 0.01 g of Copper sulphate, 5 g each of Baboolbark.On optimizing the method of mordanting, best results were obtained with Butea frondosa dye when samples were simultaneous mordanted and dyed with Alum, Babool bark and Alum. Pre-mordanting was selected for Copper sulphate. . It was found that for all the enzyme treated (acid and neutral cellulase) as well as swelling agents treated (Sodium hydroxide, Ethylenediamine and Zinc chloride) samples, the colour strength and colourfastness was increased in comparison to the untreated samples.
Highlights
Cotton is produced in over 50 countries worldwide, averaging 20-24 million tons per year
The maximum swelling caused by the Sodium hydroxide followed by cellulase enzyme treatment gave higher K/S value than Ethylenediamine and Zinc chloride treated samples followed by cellulase enzyme treatment
It was found that for all the enzyme treated as well as swelling agents treated (Sodium hydroxide, Ethylenediamine and Zinc chloride) samples, the K/S values, and the colour strength were increased in comparison to the untreated samples.Among the three swelling agents, Sodium hydroxide treated sample obtained the highest colour strength (K/S) followed by Ethylenediamine and Zinc chloride treated samples
Summary
Cotton is produced in over 50 countries worldwide, averaging 20-24 million tons per year. The preparation processes of cotton textiles include singeing, desizing, scouring, bleaching and mercerization These treatments remove natural and human induced impurities, i.e., non-cellulosic constituents and other unwanted substances and increase the affinity of cellulose for dyes and finishes. Thakare (2006) studied the treatment of hydroxylamine sulphate at various concentrations and temperatures on moisture regain and dye uptake on cotton fibre. The dyeing results showed that the Reactive dye content (Amectic Red EB Ex H/C) from 2.27 g/kg of fibre for control increased to 2.87 g/kg fibre, when the treatment was carried out by 60% w/v concentration of hydroxylamine at room temperature. Nair (2006) studied the changes in fine structure of native cotton cellulose as a result of three typical swelling treatment viz., with Sodium hydroxide (NaOH), Ethylenediamine (EDA) and Zinc chloride (ZnCl2). The de-crystallizing action of the three swelling agents were in the order: NaOH>EDA>ZnCl2> Native cotton on treatment with swelling agents, showed decrease in absolute crystallinity or lateral order and a decrease in both crystallite length and width
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